One of the usual requirements in producing quality concrete is the proper manipulation of the concrete during curing. Curing not only increases the strength of concrete and its structural value, but proper curing during the curing period is mandatory for the production of water-tight and durable concrete. During the concrete curing process, chemical changes occur in the presence of water which ensure that the hardened concrete will be water-tight and durable over time, resulting in a stable and sturdy cured physical structure. These chemical changes occur over a considerable period of time requiring that the concrete be kept wet after it has set during the curing period. However, one problem is that the heat radiating from the concrete during the curing process evaporates the moisture in the concrete, thereby inhibiting the chemical hardening process and compromising the strength and durability of the cured concrete.
It is therefore necessary to contain the heat and moisture in the concrete long enough to permit the curing process to be sufficiently completed. Not surprisingly, the need for heat and moisture retention increases during cold weather applications. With decreasing temperatures, the need for increased thermal retention requires the use of additional layers of insulation, resulting in concrete cure blankets of greater thickness which are heavy and cumbersome to use. It would be advantageous to have a lightweight multilayer moisture-impervious heat reflective concrete cure blanket that is capable of providing enhanced thermal resistance without a corresponding increase in the thickness or weight of the blanket.
Conventional moisture-impervious concrete cure blankets use combination foam, Fiberglass, air filled bubble layers, and like materials as insulative layers. However, such blankets are susceptive to accidental rips, and in the event the interior insulation gets wet, the insulating quality of the insulation material is reduced. Another method to keep the curing concrete moist utilizes frequent sprinklings, but this approach is labor intensive and expensive. To promote curing, horizontal concrete surfaces are usually covered by sand, canvas or burlap to maintain the desired dampness. But irregular and/or vertical concrete surfaces cannot be adequately covered and have to be sprinkled periodically to maintain the required damp condition. Concrete cure blankets are typically used to cover water-wetted concrete to extend the duration of the damp condition for as long as possible. It would be advantageous in the art to have a lightweight and durable, multilayer, moisture-impervious, heat reflective concrete cure blanket having enhanced thermal resistance and which is also universal in use in that it can be used for curing either horizontal or vertical concrete structures regardless of size. It would also be advantageous to provide a lightweight and durable heat reflective concrete cure blanket which is inexpensive to produce, and may be discarded after use.
One prior art attempt to solve these problems is taught by U.S. Pat. No. 5,549,956 to Handwerker, the present inventor, titled “Heat Reflective Blanket” which is directed to a flexible, multilayer heat reflective blanket containing at least one interior heat reflective, (i.e., metal foil) layer, and at least one interior insulative layer. It has been discovered that a heat reflective concrete cure blanket configured to include an insulative layer as well as a heat reflective layer improves and enhances the effectiveness of the blanket, thereby making the blanket more efficient for its intended use. While the blanket disclosed in U.S. Pat. No. 5,549,956 satisfactorily enhances the concrete curing process, the configuration of this type of concrete cure blanket is somewhat expensive. It would be an advantage in the art if a lightweight, multilayer, moisture-impervious, heat reflective concrete cure blanket could be manufactured inexpensively, and yet also be durable and long-lasting.
Another approach to solve the above problems is taught by U.S. Pat. No. 4,485,137 to White titled “Concrete Curing Blanket” which is directed to a lightweight summer concrete cure blanket which improves water retention in the curing concrete irrespective of the surface irregularities present in the concrete. The cure blanket provides for effective water wicking or capillary wetting action characteristics across the entire blanket. The concrete cure blanket can be easily sealed with adjacent blankets to provide continuous coverage of a large area of curing concrete without tearing the blankets. The White concrete cure blanket has a nonporous surface layer of a low density polyethylene that is heat sealed as a coating upon a batting layer of a porous, resilient, non-woven, needle-punched, synthetic fabric such as polypropylene or commercially available polymeric filament fabric. While having a porous exterior surface layer, the opaque surface layer of this concrete cure blanket will block visible sunlight and UV radiation. However, this concrete cure blanket is not suitable for winter concrete curing utilization, since the prior art blanket cannot reflect the heat radiating from the curing concrete, and the evaporation of moisture from the curing concrete remains a continuous operational problem thereby requiring rewetting of the curing concrete from time to time as needed during the curing period. It would be an advantage in the art if a lightweight, multilayer, moisture-impervious heat reflective concrete cure blanket were available to the construction industry.
Yet another attempt to provide an efficient concrete curing blanket is shown in U.S. Pat. No. 5,855,978, to Handwerker, the present inventor, which describes a concrete cure blanket having top and bottom moisture-impervious outer layers, at least one heat insulative layer disposed between the top and bottom layers, the bottom outer layer composed of a woven material with a heat reflective material applied to the lower surface of the woven material. The disclosed concrete cure blanket of this prior art patent includes a woven polyethylene layer having added reflective material applied to the outer facing surface of the lower outer layer. This differs from the present invention, which does not incorporate a woven polyethylene layer and an additional reflective layer, which provides a blanket of less weight and manufacturing costs than shown in Handwerker U.S. Pat. No. 5,855,978.
The initial costs associated with the production of various concrete cure blankets disclosed in the prior art make such blankets expensive to acquire. It would be an advantage in the art if a lightweight, multilayer, moisture-impervious, heat reflective concrete cure blanket could be manufactured relatively inexpensively and easy to maintain, or even disposable, by utilizing long-lasting thermoplastic films formed into at least one bubble type structure having a relatively small thickness and weight, in combination with reflective materials.
The present invention overcomes these and other problems that are inherent in existing multilayer and other concrete cure blankets. The present invention combines lightweight moisture-impervious, film-like outer layers formed with at least one bubble type insulative layer, and at least one heat reflective layer associated with one or both of the outer layers and/or bubble type layers to reflect heat back to the concrete, thereby reflecting heat emanating from the concrete back to the concrete to maintain heat in the concrete.
A principal object of the present invention is to provide a lightweight bubble type multilayer moisture-impervious heat reflecting concrete cure blanket that exhibits enhanced thermal reflective capability without a corresponding increase in the thickness and/or weight of the blanket.
Another object of the present invention is to provide a lightweight bubble type multilayer moisture-impervious heat reflecting concrete cure blanket that exhibits enhanced thermal resistance of the blanket by utilizing at least one heat reflective surface embodied as part of a bubble type insulative layer, which surface reflects the heat radiating from curing concrete back toward the concrete.
A further object of the present invention is to provide a lightweight bubble type multilayer moisture-impervious heat reflecting concrete cure blanket that exhibits enhanced thermal resistance of the blanket by utilizing at least one heat reflective surface, which surface reflects the heat radiating from curing concrete back toward the concrete, in combination with at least one bubble type insulative layer forming part of the blanket.
A further object of the present invention is to provide a lightweight multilayer moisture-impervious heat reflecting concrete cure blanket that exhibits enhanced thermal resistance of the blanket by utilizing a plurality of heat reflective surfaces in combination with at least one bubble type insulative layer that reflects heat radiating from curing concrete back toward the concrete.
A further object of the present invention is to provide a lightweight bubble type multilayer moisture-impervious heat reflecting concrete cure blanket that retards the rate of moisture evaporation occurring in the curing concrete by reflecting the heat radiating from the curing concrete back toward the concrete.
A still further object of the present invention is to provide a lightweight bubble type multilayer moisture-impervious heat reflecting concrete cure blanket that is easy and inexpensive to manufacture, durable and long-lasting, easy to maintain, and comprises less material and weight than previous concrete cure blankets. Such blanket could be disposable, if desired, due to its inexpensive costs of manufacture.
In accordance with one embodiment of the present invention, there is provided a lightweight bubble type multilayer heat reflective concrete cure blanket, the blanket having associated heat reflective elements associated with at least a bottom moisture-impervious layer, the blanket comprising:
a moisture-impervious first top outer layer and a moisture-impervious second bottom outer layer, the first and second layers sealingly connected to each other at the boundaries of the layers to form a moisture-impervious chamber between the first and second layers. At least one heat insulative layer is formed with the top outer layer, the heat insulative layer having a plurality of insulative elements disposed in spaced relation to each other on at least one surface of the insulative layer. The second bottom outer layer comprises either a substantially flat non-insulative heat reflective layer, or an insulative heat reflective layer of a plurality of insulative elements disposed in spaced relation to each other. The substantially flat non-insulative layer, and/or the insulative layer of the bottom outer layer has a reflective material applied thereto to reflect heat radiating off of the curing concrete back to the concrete.
These and other objects and advantages of the present invention will be set forth in the following description of the illustrated embodiments in connection with the drawings, the disclosure, and the appended claims, wherein like reference numerals represent like elements throughout.